I just ordered my Canon A620 and Housing. I would like to know what is a must have list of extras for my new system. How many Hi Def pictures can I expect on a 512 mb sd card? Should I get a 1 or 2 gig SD Card? Is the 150x fast SD cards a beter way to go? Should I get display protector sheets ASAP? Can I use my canister light, 50W 6400K as an extra lighting solution for pictures? Anyone have a protective cover to go over the underwater housing to protect the face from scratches, when camera is not in use? What about extended warranty programs?